The present invention relates to a tube slotting machine, and more particularly to a machine that provides tubing with clean slotted openings free of roughened edges.
In the past, land improvement through proper drainage was an expensive and time consuming operation. The red clay tile commonly used for this purpose required the piecing together of relatively short lengths to construct the desired subsurface drainage system. These systems were vulnerable to misalignment due to the large number of lengths required to construct them, and extreme care was required when the system of tiles was covered with earth in order to avoid breakage of the tile material. For the most part, corrugated drainage tubing manufactured from polyethylene and the like has now replaced the heretofore drainage systems of tile pieces.
The tubing used for subsurface drainage systems is corrugated for flexibility and strength. An arrangement of slotted openings in the tubing allows excess water from the surrounding earth to enter the tubing and thereby be conveyed away by the drainage network. Usually, a minimum of one square inch of slotted open area is required from each one foot length of tubing.
Generally, these slotted openings are located in the center of the corrugation valley with not less than three rows around the circumference of the tube. Usually the slotted openings are 1/16 inch wide, and range in lengths from 1 to 11/2 inches depending on the diameter of the tube. It is highly desirable that the openings be relatively clean and well formed and located in the corrugation valleys.
At present, the slotted openings in corrugated tubing are generally produced by cutting machines using rotary saw blades. These blades are mounted on arbors in any number ranging from a single blade to as many as eighteen or more blades. In operation, the blades rotating at significantly high speed are brought into contact with the tubing in a radial direction so that the blades register with the corrugation valleys. Utilization of rotary saw blades has certain drawbacks since these blades rapidly become dull which results in the slotted openings having badly roughened peripheral portions. Even when the blades are sharp, a certain amount of peripheral roughness exists. These roughened portions trap and collect foreign material which decreases the efficiency of the drainage system.
Another problem encountered by using saw blades involves registry of the blades with the valley center lines. Also, an accumulation of dust results from the sawing operation, and the procedure is quite noisy and very dirty.
Other methods of producing slotted openings or drainage areas in the exterior of corrugated tubing have been utilized such as drilling, punching, and cutting the tops off of indentations or protrusions molded in the tube, for example. However, these procedures have the same drawbacks mentioned above. Also power consumption in the operation of drilling and punching equipment is high.